I have a long activity diagram, includes conditionals, but is basically long and thin. There are two options I could imagine to fix it:
For some sequences of activities, I could go right then left to use more horizontal space where there is nothing interesting going on in conditional space, but there are multiple steps, something like
:A; -> :B; -> C;
:D: -< E:; -< F;
would result in A B and C going horizontally and then D below C and going back left horizontally ... (there might be a syntax for this already, but if so I haven't found it ... the syntax I've used here is just to show the idea, I'm sure it wouldn't be the right one).
One could do
which would result in the arrow from M going back to the top of the page and down into a new column of N and subsequent activities (this is *not* a swimlane, just artificailly creating new "columns" to use more horizontal page). Again, maybe there is a syntax, but I haven't found it.